Relationship between apex cardiogram and left ventricular pressure events in Greyhound dogs.

Temporal relationships between the left apex cardiogram (ACG) and left ventricular and aortic pressure events were studied in 10 anesthetized Greyhound dogs. A close relationship existed between onset of the upstrokes of the ACG and left ventricular pressure. The nadir of the protosystolic upstroke of the ACG invariably occurred after the peak rate of change of left ventricular pressure increase (d/dt)LVP and the onset of aortic pressure increase, but occurred virtually simultaneously with the peak rate of change of aortic pressure increase (d/dt)A. The relationship between the protodiastolic nadir of the downstroke of left ventricular pressure and that of the ACG was close but variable. The ACG could be of value as a noninvasive examination technique in canine cardiovascular studies.